Detection of nontransient processing anomalies in vacuum manufacturing process

ABSTRACT

A sensor, such as a mass spectrometer, capable of detecting the presence of materials in a sampled gas is interconnected with a processing chamber of a vacuum manufacturing tool. The sensor includes a timing circuit which is activated only if certain levels of specific materials are detected. Furthermore, the timer is set to run a predetermined time interval after activation so as to discriminate between known transient processing conditions and the presence of impurities which can greatly influence the manufacturing process. When the timer exceeds the predetermined time duration, an output signal can alert the process operator or automatically shutdown the manufacturing tool.

CROSS REFERENCE TO RELATED APPLICATION

Reference is made to and priority claimed from U.S. ProvisionalApplication Ser. No. 60/093,960 filed Jul. 24, 1998, entitled USE OFMASS SPECTROMETER IN VACUUM MANUFACTURING PROCESS.

FIELD OF THE INVENTION

The invention relates to the field of semiconductor wafer processing,and in particular to utilization of a mass spectrometer or similarsensor in conjunction with manufacturing or processing apparatus fordetection of aberrant conditions, such as the presence of certaincontaminants on a semiconductor substrate.

BACKGROUND OF THE INVENTION

Many manufacturing processes which occur in a vacuum or other controlledatmosphere are sensitive to levels of one or more contaminants, processby-products, or other substances present in a process chamber(s).

In the field of semiconductor substrate manufacturing, PVD (PhysicalVapor Deposition) metallization cluster tools require a complex vacuumsystem to ensure low partial pressures of water, oxygen, nitrogen andhydrocarbons. These compounds act as contaminants which degrade thequality of different metal films deposited by sputtering. Therefore, thepresence of these compounds must be continuously monitored to safeguardprocess quality.

Residual photoresist present on a semiconductor (e.g., silicon) waferwhich is about to undergo sputter deposition of metal (e.g., aluminum)interconnects is a typical example of such an undesirable contaminant ina semiconductor manufacturing process. If the photoresist-contaminatedwafer reaches the sputter module, and the deposition process isinitiated, then the sputter module will be severely contaminated by thephotoresist. The wafer being processed will be irreparably damaged, andthe sputter module will have to be cleaned before further wafers can beprocessed. The process of cleaning a sputter module is both timeconsuming and expensive.

Current semiconductor sputtering tools generally employ a separateprocess chamber wherein the wafer, after it is inserted into the overallmanufacturing tool, can be degassed before further processing. In thischamber, the wafer is rapidly heated to drive off normally adsorbedcontaminants such as water vapor. The degas module removes water byheating the wafer either with tungsten/halogen lamps while under vacuum,or by placing the wafer on a heated chuck while argon flows on the backside of the wafer. If the wafer is also contaminated with residualphotoresist, gases characteristic of the specific type of photoresistpresent will be desorbed from the wafer. When small amounts ofphotoresist remain on the wafer, the above degas step will causepyrolysis of the photoresist which breaks the large polymer moleculesinto several certain gaseous compounds.

It is known that the presence of gases can be determined in a sampledgas environment using a mass spectrometer, such as those manufacturedand sold by Leybold Inficon, Inc. of East Syracuse, N.Y. The presence ofgases is determined by use of partial pressures of the environment andthe gas(es) in question. Using a mass spectrometer, it is possible tomonitor the levels of these characteristic gases by measuring the signalintensities of the appropriate mass-to-charge ratios of ions produced bythese substances. If the signals at these masses exceed somepredetermined upper limit during the degas process, it can be concludedthat excessive amounts of photoresist are present.

Though ordinarily, it would seem likely to perform such a measurement,it is also known that modem semiconductor processing tools have beendeveloped which allow simultaneous processes to be occurring in variouschambers connected to the tool. Therefore, and when a wafer istransferred from one of these other modules (chambers) to the waferhandling chamber to which the degas module is attached, a pressure burstmay occur in the degas module. This pressure burst can cause erroneouslyhigh levels of the masses being monitored by the mass spectrometer. Ithas been determined, however, that the duration of the signals producedby pressure bursts extend over a period of time which is significantlyshorter than that of the degas process itself.

There is a need to provide a detector which is able to measure withcertainty the small amounts of compounds which are produced whenresidual photoresist undergoes pyrolysis at the degas module, in orderfor the process to be halted, so as to prevent further contamination ofPVD modules, and the extensive downtime required to clean the modules.

SUMMARY OF THE INVENTION

It is an object of the present invention to improve the state of the artof semiconductor manufacturing processes.

It is a further object of the present invention to detect the presenceof impurities on a semiconductor wafer prior to high level vacuumprocessing so as to prevent downtime of a manufacturing tool.

It is yet a further object of the present invention to integrate thedetection of impurities into the processing protocol either to allowautomatic shutdown of the tool, or at a minimum, to notify the operatorof a contamination condition.

Therefore and according to a preferred aspect of the present invention,there is provided a processing apparatus for determining the presence ofaberrant conditions in a manufacturing process, said apparatuscomprising:

a manufacturing tool having an interior within which said manufacturingprocess is performed and control means for controlling saidmanufacturing process; and

a sensor in communication with the interior of said manufacturing tool,said sensor having means for determining mass constituents of at leastone sampled gas created during said manufacturing process and producingsignals indicative of the intensities of said constituents, said sensorfurther including means for detecting when signals produced by saidsensor has exceeded a predetermined value.

Preferably, the detecting means includes a timing circuit which allowsthe sensor, preferably a mass spectrometer, to distinguish the presenceof signals which are characteristic of transient processingcharacteristics in comparison to longer signals that are representativeof an acute processing problem, such as the presence of certainimpurities. According to a preferred technique, an algebraic Booleanexpression, using AND and OR logic, can be created to initiate thetiming circuit only if certain binary conditions (e.g., meeting apredetermined ion current limit) are met.

Using similar logic, other processing conditions having output variablescapable of being converted into binary values can also be monitored. Thepresence of such conditions, as evaluated through the above Booleanlogic, can produce a signal which can be directly input to themanufacturing tool to terminate the process automatically or at aminimum to alert an operator thereof.

According to another preferred aspect of the invention, there isprovided a processing apparatus for determining the presence ofnontransient conditions in a semiconductor substrate manufacturingprocess, said apparatus comprising:

a manufacturing tool having an interior including a plurality ofchambers within which said semiconductor substrate manufacturing processis performed and control means for controlling said manufacturingprocess; and

at least one sensor in communication with the interior of saidmanufacturing tool, said sensor being a mass spectrometer having meansfor determining mass constituents of at least one sampled gas createdduring said manufacturing process and producing representative signalsindicative thereof, said sensor further including means for detectingsignals produced by said sensor which have exceeded a predeterminedvalue including a timer which is activated only upon detection ofsignals exceeding the predetermined value.

Preferably, the timer includes means for sending an output signal tosaid manufacturing tool if said timer exceeds a predetermined durationand is connected to said control means to cause termination of themanufacturing process automatically.

The sensor is preferably a mass spectrometer having means for producingand detecting ions having specified mass to charge ratios, saiddetecting means being capable of detecting representative signals ofsaid specified ions, said sensor further including a plurality ofrelays, each relay having at least one setpoint which is triggered whenat least one specified ion signal has exceeded a predeterminedintensity.

According to the invention, the triggering of setpoints of certainpreselected relays produces an output signal which is transmitted tosaid timing circuit for activating said timer. The time duration of saidtimer is selected to be greater than the known time duration oftransient processing effects produced within the manufacturing tool suchthat the output signal generated by said timing circuit effectivelyscreens the transient processing effects.

According to yet another preferred aspect of the invention, there isprovided a method for determining the presence of nontransientprocessing conditions in a manufacturing process, said method includingthe steps of:

sampling specified mass constituents of at least one gas present withinthe interior of a manufacturing tool used in said manufacturing process;

activating a timer only if predetermined levels of certain massconstituents of said at least one gas are exceeded, said timer being setto a predetermined time interval which is greater than known durationsexhibited by transient processing conditions; and

outputting a signal if said timer exceeds the predetermined timeinterval.

The method preferably includes the step of automatically terminating themanufacturing process if the timer exceeds the predetermined timeinterval or at a minimum to alert a process operator if the timergenerates said output signal.

The sensor capable of performing the sampling, (e.g. a massspectrometer) preferably has a set of relays which are part of thetiming circuit or alternately the sensor includes relay logic includinga plurality of setpoints which can be separately triggered when at leastone signal exceeds a preselected value, said method including the stepsof:

identifying materials present in anomalous processing conditions; and

preselecting the setpoints of said sensor in accordance with maximumlevels of mass constituents corresponding to the identified materials.

Most preferably, the above timing step is initiated only upon thetriggering of a predetermined combination of said setpoints. The abovemethod has been demonstrated to be particularly effective in identifyingthe presence of photoresist in a vacuum deposition process.

An advantage of the present invention is that the inclusion of a timercircuit in combination with a sensor as described above allows thepresence of normal processing steps, such as pressure bursts, to bediscriminated against longer duration signals which are more likely tobe indicative of contamination or other long-term conditions.

A further advantage is that the manufacturing tool is configured toreceive input from the above circuit directly and to alert the operatorof the processing apparatus if a predetermined condition is met.

These and other objects, features, and advantages will be readilyapparent from the following Detailed Description which should be read inaccordance with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a typical semiconductor manufacturingprocessing tool;

FIG. 2 is a partial schematic diagram of a mass spectrometer used inaccordance with a preferred embodiment of the present invention;

FIGS. 3 and 4 are portions of schematic diagrams of a timing circuitused between the manufacturing tool of FIG. 1 and the mass spectrometerof FIG. 2; and

FIGS. 5-9 are graphical data representations taken using the massspectrometer of FIG. 2 in the buffer chamber of the manufacturingcluster tool of FIG. 1, illustrating ion current differences output overtime during several different events in the tool, including degasprocessing, to detect the presence of residual photoresist and todiscern between false negatives indicative of other operations in thetool.

DETAILED DESCRIPTION

Prior to describing the present invention, background information isherein provided in conjunction with FIG. 1 which illustrates the generalconfiguration of a typical PVD (Physical Vapor Deposition) manufacturingtool 10. The chamber illustrated, for purposes of the followingdiscussion, is an Endura 5500 PVD cluster tool manufactured by AppliedMaterials, Inc. The tool 10 is equipped with a pair of degas modules orchambers 14, 18. Typically, the above tool 10 includes a minimum of oneand a maximum of two degas modules. The degas modules 14, 18 areattached to a buffer chamber 26, along with two load lock modules 30, 34and a pair of sputter etch modules 38, 42.

There are typically four (4) wafer processing modules 46 which areconnected to an adjacent transfer chamber 50. The buffer chamber 26 andtransfer chamber 50 are separated from one another by a pair ofcool/pass-through modules 54, 58, at least one of the pass-throughmodules being set up for rapid cooling of processed wafers and whichemploys several torr of argon or other suitable gas as a heat transfermedium.

Each of the degas modules 14, 18 have no pumps of their own.Furthermore, each of the above modules 14, 18 are also not isolated fromthe buffer chamber 26. As a result, whenever valves (not shown) areactuated to any other module connected to the buffer chamber 26, a gasburst is observed in the degas modules 14, 18. These bursts arise fromthe load lock modules 30, 34, which are only rough pumped, and from thecool/pass through modules 54, 58 which are not pumped before beingopened to the buffer chamber 26. As detailed below in greater detail,these gas bursts, especially those bursts in which argon pressure is notoften well controlled at a nominal value (e.g., two torr), aresufficient to cause a momentary or transient over pressure condition inan attached mass sensor. The duration of these pressure bursts istypically less than five seconds, however, the presence of the abovebursts is sufficient to occasionally cause an over-pressure trip outcondition of the apparatus.

In operation, the degassing within the degas modules 14, 18 isaccomplished by illuminating the front surface of a retained wafer withintense light from a plurality of quartz/halogen bulbs (not shown). Theduration of a typical degas process is typically on the order ofapproximately 10-200 seconds. Details regarding this portion of theoperation are known to those of ordinary skill in the field andtherefore require no further discussion. Due to complex algorithmsutilized by the manufacturing tool 10 to maximize wafer throughput,there is no guaranteed temporal relationship between the interfering gasbursts and the degas cycle. That is to say, several different operationscan be occurring simultaneously, in different chambers of themanufacturing tool 10.

A typical sequence of semiconductor wafer processing is as follows:First, the manufacturing tool 10 takes a wafer (not shown) from acassette (also not shown) in one of the load lock modules 30, 34 andtransfers the wafer into the buffer chamber 26, after which it is placedin one of the degas modules 14, 18. After orienting and degassing in themanner described above, the wafer is brought back into the bufferchamber 26 and is then inserted into one of the sputter etch modules 38,42. Following this processing, the wafer is again sequentiallytransferred into the buffer chamber 26, into a cool/pass through module54, 58, and then into the transfer module 50. The wafer is then placedinto a succession of deposition and sputtering modules 46, after whichthe wafer is reinserted into one of the cool/pass-through module 54, 58,followed by the buffer chamber 26, and finally back into one of the loadlock modules 30, 34 where the wafer is removed from the manufacturingtool 10. It should be pointed out that in a mass production settingseveral wafers are typically being processed simultaneously, and in anoverlapping manner according to the above protocol, thereby adding tothe overall complexity of the manufacturing process.

If a wafer is contaminated with residual photoresist from a precedingprocessing step, this contamination will also contaminate themanufacturing tool 10. Contamination of either degas module 14, 18 is arelatively minor problem, resulting in downtime of a few hours, sincethe base vacuum is typically in the E-07 torr range. Similarcontamination of a process module, such as one of the sputtering anddeposition module 46, however, would require extensive downtime in thata total wet clean would be required, along with replacement of thesputtering target, shields, and associated equipment. The extent of thisdowntime could be several days.

The most common photoresist problem occurs when a coated wafer is notcompletely ashed, i.e., some of the photoresist remains. Thismisprocessing is estimated to be about one thousand times more commonthan the situation in which the wafer is not ashed at all. Misprocessingof wafers happens frequently enough to be a significant impediment tofabrication throughout processing.

The embodiment described herein utilizes a residual gas analyzer(hereinafter referred to as an RGA) 62, FIG. 2, such as the TSP C100Mquadrupole mass spectrometer manufactured by Leybold Inficon, Inc. Itshould be readily apparent that other suitable instruments can besubstituted employing the concepts described herein. The above RGA 62,shown partially in FIG. 2, is described completely in the TRANSPECTORGas Analysis System Manual, published by Leybold Inficon, Inc. asrevised March, 1997, which is incorporated by reference in its entirety.

Referring to FIGS. 1 and 2, the RGA 62, is preferably installed throughknown means to either a port on the buffer chamber 26 or directly to oneof the orient/degas modules 14, 18, of the semiconductor processing tool10, all of which are pumped to high vacuum by a buffer cryo pump (notshown). According to the present embodiment, the mass spectrometerportion 64, shown in part schematically in FIG. 2, and the electronicsportion (not shown) of the RGA 62 are installed on the wall of one ofthe degas module 14, using a 90 degree CF flange elbow (not shown) orother known means mounting thereon, preferably in a vertical position.

In brief and referring to FIG. 2, the mass spectrometer portion 64 ofthe RGA 62, FIG. 3, includes an ion source 66 including an electronemitter (not shown) which emits electrons that pass through an openingin an ionization chamber having an ionization volume 68 containingrarified gas. The electrons interact with the gas molecules, and ionizewith some of the molecules. The ions which are produced are acceleratedby a focus plate or ion lens assembly 70 through an opening into an ionbeam which is focussed through a quadrupole mass filter 74. The massfilter 74 separates ions contained in the focussed ion beam (not shown)based on mass to charge ratios, permitting certain ions to passtherethrough onto an ion collector or detector 78, such as an electronmultiplier, which is interconnected by known means to an electrometer80. Additional details relating to the ion source, the ion detector,electrometer and the electronics portion of the RGA 62 are provided, forexample, in the cross referenced TRANSPECTOR Manual referred to aboveand do not form a specific part of the present invention, except asindicated herein

The electronics portion (not shown) includes software which allowsrepresentations, such as mass spectra and other graphical output, suchas those illustrated in FIGS. 5-9, and described below based at least inpart on masses which are selected to pass though the quadrupole massfilter 74.

Referring to FIGS. 3 and 4, a timing circuit 100 is attached to the RGA62. According to the present embodiment, the timing circuit 100 includesa number of electrical relays 82, 84, 86, each of which include a pairof selectable set points. In the present sensor device, three (3)electrical relays are provided, each having two set points to monitoroutput signals from the RGA 62. In this embodiment, a total of six (6)mass or AMU settings of the atmosphere within the manufacturing tool 10are monitored, though it should be readily apparent that incorporationof additional or fewer relays is acceptable, depending on theapplication. Additionally, and though the present sensor includesindividual relays 82, 84, 86, it should be readily apparent that therelay conditions can be similarly duplicated through other signaldevices or through software having sufficiently programmable logicelements to mimic the relay settings.

A sample “recipe” is devised for certain identified masses which aresuitably formed in photoresist pyrolysis. For purposes of the followingchart, the following masses 15, 28, 31, 44, 64 and 86 AMU have beenidentified and are defined for the following example recipe chart whichconstitute the masses of ions characteristic for degassed I-linephotoresist.

AMU Product Wafer 20 Sec Ash Trigger Set 15(2) 5.0 E-10 6.00 E-082.00E-08 28(1) 1.00E-08 1.00E-07 2.00E-08 31(2) 1.00E-11 2.00E-082.00E-09 44(1) 7.70E-10 2.00E-07 5.00E-08 64(3) 3-00E-12 1.00E-091.50E-10 86(3) 4.00E-13 4.00E-10 1.50E-10

Each of the units shown are in amps and are defined ion current valueswith the number in parentheses representing the number relay which isset to the particular trigger point based on the empirical data of theproduct wafer and 20 sec ash columns. The outputs of each of theelectrical relays 82, 84, and 86 are “added” together according to thisembodiment by placing jumper wires in the I/O connector 61 of the RGA 62as shown in FIGS. 3 and 4 through the connection of relay pin 81 to pin83 and relay pin 85 to pin 88, as shown. That is, all three relays 82,84, and 86 must be activated for proper photoresist detection. In serieswith the three relays 82, 84, 86 is a power supply 87 having sufficient,voltage (in this instance +24 volts) to enable activation of a timedelay relay 90 which is attached thereto. According to the presentembodiment, the time delay relay 90 is a C10 Series TDR sold by theAmerpite corporation or other commercially available relay of anequivalent type.

An algebraic Boolean expression is therefore derived for use with thethree relays 82, 84, 86 as follows:

E =([28] OR [44]) AND ([15] OR [31]) AND ([64] OR [86]) in which thebracketed values indicate those masses specified in the preceding chart.The bracketed values are represented by the set points in which binarylogic dictates; that is either 1 or 0, whether the ion currents measuredexceed the programmed set points.

According to the present embodiment, and when all three relays 82, 84,86 are tripped; that is, the above Boolean expression is satisfied, +24volts from the power supply 87 is placed on the input pins 95 of thetime delay relay 90. The application of voltage from the power supply 87starts an adjustable timer 98 set for a predetermined interval.According to the present embodiment, the timer 98 is set forapproximately 6 seconds. After this interval has been exceeded, thetimer delay relay 90 will trip automatically, sending an appropriatesignal as input to the manufacturing tool 10 to cause shutdown or, at aminimum, will trigger an audible or other suitable alarm (not shown),thereby indicating the presence of photoresist.

More specifically, the present manufacturing tool 10 requires an opencircuit for error detection. Therefore, the connection of themanufacturing tool 10 is wired to the normally closed pins 97, 99 of thetime delay relay 90. A multi-pin connector 94 is used to connect thetime delay relay 90 to the manufacturing tool 10, shown schematically inFIG. 4, with pins 91, 93 being used to make the connection to themulti-pin connector 94 according to the present embodiment.

Preferably, depending on the recipe and masses selected, the describedRGA 62 is able to detect the presence of either I-line or DUV (DeepUltra Violet) residual photoresist during the degas process, andtherefore positively identify the presence of contamination upon adegassed wafer by monitoring different signals which are specific tophotoresist pyrolysis and employing a method that ignores brief highpressure events which produce false detection. Preferably, thecontamination signal is fed directly into the manufacturing tool 10 tohalt further process, to allow rework of the contaminated wafer, and toassure that no contamination is spread to deposition modules.

In summary, as to this embodiment, and by monitoring the intensities ofspecified masses (depending on the type of photoresist present) andsetting alarm thresholds with logical OR-ing and AND-ing of the relayoutputs using the above or other suitable Boolean expression, along witha predetermined timer delay (in this instance approximately six (6)seconds), it is possible to detect the presence of photoresist with ahigh degree of accuracy and without false indications.

Reference is now made to FIGS. 5-9 which illustrates graphicalrepresentations as measured by the RGA 62, as attached to one of thedegas modules 14, FIG. 1. Each of FIGS. 5-9 are defined along the x-axisby a series of chronological scan numbers presenting a timed sequence asread from left to right. The y-axis of each graph indicates ion current,measured in amps by the detector portion of the mass spectrometer andillustrated in specified ranges between figures in order to clearlyillustrate the effectiveness of the present invention. For purposes ofthe discussion which follows, it should be noted that each scan numberrepresents approximately ⅔ of a second.

In the present example, the characteristics of degas processing of twodifferent wafers are monitored and compared. As most clearly shown inFIG. 7, the degas operations are for a partially ashed wafer (commencingat scan number 330 and ending at scan number 390) and a test wafer(labeled TEOS) having no photoresist present (commencing at scan number471 and ending at scan number 532).

By sensitizing the mass spectrometer for particular mass to chargeratios, specific masses can be easily targeted. Each of the degasprocedures shown are approximately 40 in duration, though as noted abovethese periods can range between 10-200 seconds. Specific mass settingsare selected in each of the above graphs to illustrate comparatively theoccurrence of other events in the manufacturing tool affecting themeasured output, such as opening of either of the load lock modules or acool argon burst are much shorter in duration than the degas process. Onaverage, each of the preceding events occur over less than 6 scannumbers, or less than about 4 seconds.

As clearly discernible from FIGS. 5-9, each of the non-degas producingevents will cause increases in the measured ion current, which,depending on the masses selected and shown by the appropriate legends ofeach chart, which are in excess of a predetermined trigger value.However, because the signal is not sustained for a sufficient duration(less than 6 seconds), the timer relay 90 does not send a signal to themanufacturing tool 10. Note that a load lock and a argon blast eventoccurs during each of the above degas processes, but that only the scanportion between about 360 and 390 has voltage values for an adequatetime duration sufficient for triggering. As most clearly observed fromFIG. 6, and without the use of the above timer circuit, it would not bepossible to use a mass spectrometer with the tool 10 using appropriateion current limits without the regular occurrence of false indications.

Though the present embodiment utilizes a timer relay which is separatelyutilized with the electrical relays of the described mass spectrometer,alternate embodiments can include modifications to the logic of thesoftware of the mass spectrometer to incorporate the above relay Booleanlogic (OR-ing and AND-ing) into timer functions. Preferably, firmwarebetween the manufacturing tool and the mass spectrometer can also bemodified to detect the presence of residual photoresist, in the event ofcomputer failure.

In addition, and though the above embodiment relates specifically to thedetection of photoresist without false negatives, it should be readilyapparent to one of sufficient skill in the field that additional binaryvariables corresponding to a particular parameter or state of theprocessing tool, or any other processing variable in a two-state format(e.g., plasma power above or below a predetermined limit, the presenceof absence of a wafer in a specified processing module, degas modulelamp power being above or below a pre-specified value, the opening andclosing of slit-valves, etc.) can be utilized into a Boolean algebraicexpression. The value of the output variable of the Boolean algebraicexpression selected can then be used to determine whether additionalprocessing should be attempted. As in the preceding, this determinationcan be made automatically (via a direct electrical input to themanufacturing tool or through a computer interface to the massspectrometer and the tool) or by a human operator.

PARTS LIST FOR FIGS. 1-9 10 cluster tool 14 degas module 18 degas module26 buffer chamber 30 load lock module 34 load lock module 38 etch module42 etch module 46 wafer processing modules 50 transfer chamber 54pass-through module 58 pass-through module 61 I/O connector 62 residualgas analyzer (RGA) 66 ion source 70 lens assembly 74 quadrupole massfilter 78 ion detector 80 electrometer 81 relay pin 82 relay 83 relaypin 84 relay 85 relay pin 86 relay 87 power supply 88 relay pin 90 timerdelay relay 91 pin 92 jumper cables 93 pin 94 connector 95 input pins 97pin 98 timer 99 pin 100 timer circuit

We claim:
 1. A method for determining the presence of nontransientprocessing conditions in a manufacturing process, said method includingthe steps of: sampling specified mass constituents of at least one gaspresent within the interior of a manufacturing tool used in saidmanufacturing process; activating a timer only if predetermined levelsof certain mass constituents of said at least one gas are exceeded, saidtimer being set to a predetermined time interval which is greater thanknown durations exhibited by transient processing conditions; andoutputting a signal if said timer exceeds the predetermined timeinterval, said tool further including a sensor having a plurality ofsetpoints which can be triggered when a preselected value is exceeded,said method including the additional steps of: identifying materialspresent in anomalous processing conditions; and preselecting thesetpoints of said sensor in accordance with maximum levels of massconstituents corresponding to the identified materials.
 2. A method asclaimed in claim 1, including the step of alerting a process operator ifsaid timer generates said output signal.
 3. A method as claimed in claim1, including the step of automatically terminating the manufacturingprocess if said timer exceeds the predetermined time interval.
 4. Amethod as claimed in claim 1, wherein said timer activating step isinitiated only upon the triggering of a predetermined combination ofsaid setpoints.
 5. A method as claimed in claim 1, including the step ofselecting the mass constituents in accord with those materials presentas photoresist in a vacuum deposition process.